A non-volatile memory in next generation have been developed to realize that rewriting speed and number of rewriting of the non-volatile memory are higher than and five orders of magnitude larger than those of a conventional EEPROM or a conventional flash memory, respectively. Furthermore, it is desirable that characteristics of the non-volatile memory such as capacity, speed or cost are comparable with those of a conventional DRAM.
A FeRAM (Ferroelectric Random Access Memory), a MRAM (Magnetic Random Access Memory), a PRAM (Phase Change Random Access Memory), a RRAM (Resistive Random Access Memory) or the like are nominated as the next generation non-volatile memory. A memory cell in a FeRAM is composed of a ferroelectric capacitor and a transistor as shown in Japanese Patent Publication (Kokai) No. 2002-217381 (P15, FIGS. 2 and 5), for example.
As shown in Japanese Patent Publication (Kokai) No. 2002-217381 (P15, FIGS. 2 and 5) or the like, miniaturization of the ferroelectric capacitor and the transistor in plane is necessary for highly integrating the memory cell of the FeRAM. However, there are several problems. For example, a lithographic limitation causes a physical limitation in the miniaturization in plane. Moreover, degradation of the ferroelectric capacitor and the transistor is produced by the miniaturization. Therefore, desirable characteristics of the FeRAM cannot be retained.